To meet the demand for downsizing semiconductor devices, a surface mount package is widely used in which a metal frame serving as a bonding pad is provided at the back surface. The semiconductor devices having the surface mount package are mounted using the reflow soldering, for example, on a printed circuit board on which a solder paste is printed. It is confirmed that the semiconductor device is properly fixed to the printed circuit board, when a solder fillet is observed on the side surface of the package. That is, the solder wettability of the frame can be examined by observing the presence or absence of the fillet, which is the climbing-up solder formed on an end face of the frame that is exposed at the side surface of the package.
However, for example, the solder may penetrate into a gap between the resin package and the frame subsequently after climbing up the end surface of the frame, reducing the reliability of the semiconductor device. Therefore, it is desired for a semiconductor device to enhance the reliability by suppressing the solder intrusion at the side surface of the package.